Process for reducing a three-phase fluid system to a two-phase system



Feb. 3, 1959 G. c. CAVANAGH 2,872,466

PROCESS FOR REDUCING A THREE-PHASE FLUID SYSTEM TO A TWO-PHASE SYSTEMFiled NOV. 27, 1956 2 Sheets-Sheet 1 .Zfa. 1.

Mile

Grapes: C. CWV/I/l/i/i INVENTOR.

HUEBNER, BEEHLER, WORREL & HERZIG ATTORNEYS 7 BY M%W Feb. 3, 1959 G. c.CAVANAGH 7 PROCESS FOR REDUCING A THREE-PHASE FLUID v SYSTEM TO ATWO-PHASE SYSTEM Filed NOV. 27, 1956 2 Sheets-Sheet 2 650/665 L".CiVi/Vifi INVENTOR.

Maia/5e, 559/456. waleez #562/6 Anne/M545 PROCESS FOR REDUCING ATHREE-PHASE FLUID SYSTEM TO A TWO-PHASE SYSTEM George C. 'Cavanagh,Fresno, Califl, assignor to Ranchers Cotton Oil, Fresno, Calif.

Application November 27, 1956, Serial No. 624,701

9 Claims. (Cl. 260-428) The present invention relates to the art of oilrefining and more particularly to a continuous process for reducing athree-phase fluid system of agglomerated solid constituents in a liquid,some of which solid constituents are heavier than the liquid and othersof which are lighter than the liquid because of volatile materialentrapped therein, to a two-phase system for subsequent gravitationalseparation. The instant invention resulted as a solution to the problemof reducing such a three-phase system to a two-phase system, in whichthe threephase system consisted of a miscella of oil in a suitablesolvent therefor, such as hexane, and which system containedagglomerations of soapstock, some of which agglomerations were renderedlighter than the miscella by the entrapment of solvent therein. Thesucceeding description of the continuous process for convenience makesreference to such utilization but it is to be borne in mind that theinvention is not limited to this specific use, being applicable to anycomparable operation. Further, in referring to three-phase systems it isthe intent to include all multiple phase systems more than two-phasewhich may result by entrapment of volatile constituents in solidagglomerations.

This application is a continuation-in-part of my prior co-pendingapplication Serial No. 366,458, filed July 7, 1953 entitled Extractionand Refining of Glyceride Oils and Fats From Source Materials Thereofissued April 16, 1957 as U. S. Patent No. 2,789,120. I

One of the difficulties previously believed inherent in the miscellarefining of oils and fats was the removal of soapstock from the miscellaafter the treatment of the oils or fats with an alkaline reagent forrefining purposes. Normally soapstock itself is heavier than suchmiscellas of oils or fats and solvents. However, during the practice ofmiscella refining processes portions of the-solvents become entrapped inthe agglomerations of the soapstock as they are formed or duringsubsequent processing. The entrapped solvents impart buoyancy to some ofthe agglomerations while other agglomerations remain heavier than themiscella. This has resulted in the establishment of three-phase systemswhich have defied continuous gravitational or other separation until thepresent invention. Even when permitted to stand, the three-phase systemspersist With agglomera tions of soapstock settling to the bottom of themiscella and other agglomerations and entrapped solvent floattatesPatent consuming, has resulted in such ineffectual solvent and soapstockremoval that the resultant oils have been unacceptable for most purposesfor Which they are intended, and has been so wasteful and expensive asto render miscella refining processes virtually useless for commercialpurposes.

Prior to the present invention, efforts to break threephase systems ofthe character described to two-phase systems by heating and cooling havenot been successful in commercial operations. The procedures have beensubject to certain fatal difficulties which have heretofore beenregarded as inherent and inescapable. When such miscellas containing thebuoyant and the heavy agglomerations of soapstock are heated as much asdesired, they must be confined to avoid waste of the volatile solventand the problems of such confinement and mixing have previouslyprecluded success. The mixing has required the extension through thewalls of a confining vessel of an agitating mechanism of some typerequiring packing thereabout. It has been virtually impossible tomaintain the packing under the conditions of heat and pressure involved.Further, such batch operation has involved voluminous vessels in orderto retain the threephase systems therein for sufficient time to achievethe desired heating and cooling. The utilization of such vessels forbatch treatment has proved impractical because of the inefiicienciesinherent to such operations. The utilization of such vessels incontinuous processes has not been practical because it is impossible tomake certain that the last miscella delivered to the vessel is the lastto leave the vessel and accurately regulated treatment of the miscellahas been precluded. Additionally, in such vessel operation there is anincreased tendency for soapstock to coalesce with the sides of thevessel serving as insulation and further aggravating the problems ofheating and cooling which at best are not expeditiously performed inlarge vessels.

An object of the present invention is, therefore, to provide an improvedcontinuous process for reducing three-phase fluid systems to' two-phasesystems.

Another object is to provide a process suitable to the continuousreduction of three-phase fluid systems to twophase systems in which thethree-phase systems consist of miscellas of oils in solvents containingagglomerations of soapstock, some of which agglomerations are heavierthan the miscella and others of which are rendered lighter than themiscella because of solvent entrapped therein.

Another object is to render miscella oil refining processes commerciallypractical by the provision of an improved process for the removal ofsoapstock from the miscella.

Further objects are to provide a process of the character describedwhich is economical to perform, avoids Waste of the materials involved,permits recapture of substantially all of the solvent employed forre-use, is suitable for continuous practice, can be rapidly employed soas to permit integration into continuous miscella refineries withoutcurtailing or impeding operations, and which is dependable in theresults attained.

in the drawings:

Fig. 1 is a schematic diagram of a portion of a miscella oil refiningsystem embodying the principles of the present invention.

Fig. 2 is a fragmentary longitudinal section of a conduit employed inthe system of Fig. 1 showing bafiles optionally utilized therein.

Fig. 3 is a schematic diagram of a portion of a miscella oil refiningsystem somewhat more fragmentary than Fig. 1 and showing a second formof pump arrangement for recycling purposes.

Referring in greater particularity to the drawings:

Similar elements are given similar identifying numerals as in thepreceding application of which the instant application constitutes acontinuation-in-part. Thus, 60 designates an homogenizer through which amiscella of oil being refined and hexane, or other suitable solvent forthe oil, is recycled. The homogenizer agglomerates soapstock formed inthe oil by treatment thereof with caustic soda or other alkalinematerial and achieves a suitable break in the few seconds the miscellais-in the homogenizer. For purposes of this description, the homogenizersimply illustrates a source of a threephase fluid system which it isdesired to reduce to a twophase system. In a commercial refinerypracticing the invention, the three-phase system consists of:

(1) Miscella of cottonseed oil in hexane with the hexane being presentin amounts of from or less to 80% of the weight of the oil.

(2) Agglomerations of soapstock which are heavier than the miscella.

(3) Agglomerations of soapstock which are buoyant in the miscellabecause of hexane entrapped therein.

The homogenizer 60 is fed with the miscella through a feed line 61connected to an inlet 62 of the homogenizer. The three-phase system isdischarged from the homogenizer through a conduit 63 connected to a heatexchanger indicated generally at 70.

The heat exchanger has an economizer 69 to which the conduit 63 isdirectly connected, a heater 71 and cooler 72.

The economizer has a first coil 80, a hot coil 81, and a cold coil 82,so named for reasons which will subsequently'become apparent. The coil80 is connected to the conduit 63 and to the cold coil, as at 83. Anoutlet conduit 84 leads from the interconnection of the coil 80 and thecold coil 82 from the economizer 69. A recycling pump 85 is connected tothe outlet conduit 84 and to the heater 71. A coil 90 is provided in theheater having one end connected to the recycling pump 85 and an oppositeend. connected to the hot coil 81 of the economizer 69. The hot coil 81interconnects the heater coil 90 and the cooler 72.

A coil 95 located in the cooler 72 interconnects the hot coil 81 and aninlet end of the cold coil 82.

The structures of the economizer 69, heater 71, and

cooler 72 may take any form suitable to the heating of dium fortransmitting heat between the coils 80, 81, and

82. The tank 98 of the heater 71 may be entirely closed and have steamfrom any suitable source, not shown, supplied thereto to heat the coil90 and miscella. Similarly, the tank 99 of the cooler 72 may be a closedtank and cold water from any suitable source, not shown, may be directedthrough the tank to chill the coil 95 and miscella.

A discharge conduit 100 is connected to the cold coil 82 in theeconomizer 69 in spaced relation to the interconnection 83 and isextended from the economizer for connection to means, not shown, forgravitationally separating the two-phase system discharged therethrough.In commercial operations, a centrifuge is employed for suchgravitational separating purposes but it will be quite apparent that anysuitable means may be utilized.

The coils 90 and 95 preferably, but not necessarily,

contain bafiies 105 as shown in Fig. 2. The baflles are F for thepurpose of agitating the miscella as it is heated and cooled tofacilitate agglomeration of soapstock in tained wthout the bafiilesbecause of agitation of the miscella incident to the heating andcoollng.

Operation The three-phase fluid system is directed from the homogenizer60 through the conduit 63 into the coil 80. In the coil 80, thetemperature of the miscella is somewhat elevated so that the subsequentheating requires less energy. The miscella passes through the coil 80and out the conduit 84 to the pump 85. The capacity of the pump isgreater than the rate of flow of the three-phase system into theeconomizer from the homogenizer 60.

The partially warmed three-phase system is forced by the pump throughthe coil 90 where the system is raised to a temperature suflicient tovolatilize the solvent in the system. When hexane is employed as thesolvent, the temperature is raised to the range of from approximately140 F. to approximately 158 F. As the three-phase system is heated, thehexane, or other solvent, at least partially volatilizes impartingvigorous agitation to the system in addition to the agitation caused bythe flow over the baflles 105. The heat serves to soften soapstock inthe system so that as the entrapped solvent volatilizes it is releasedby the soapstock in the miscella. The system is directed through thecoil 90 at a rate of fiow such that it is agitated and heated in theheater for a period of from five to ten minutes.

From the heater, the fluid system is directed into the hot coil 81 whereits heat is dissipated in warming the coils and 82. Thus, although thefluid system is at from 140 F. to 158 F. as it enters the economizer, itis substantially cooler, frequently from 115 F. to 120 F. when it leavesthe economizer and flows into the cooler coil 95.

As the fluid system passes through the cooler coil it is reduced intemperature sufiiciently to condense any volatilized solvent andsufliciently to solidify previously melted or softened soapstock. Whenhexane is employed, the temperature of the fluid system is reduced to arange of from approximately 80 F. to approximately 110 F.

From the cooler coil 95, the fluid system is directed to the cold coil82 in the economizer 69 where it is heated in preparation for dischargethrough the conduit 100 or recycling through the heater and cooler.

It will be recalled that the capacity of the pump is substantiallygreater than the flow rate of the fluid system into the economizerthrough the conduit 63. This is for the purpose of compelling recyclingof the system through the heater and cooler where, in spaced relationalong the described interconnected coils constituting a conduit throughthe heat exchanger 70, the fluid system is successively heated to atemperature suflicient to soften the soapstock and to volatilize thesolvent while being stirred or agitated and subsequently cooled to atemperature sufficient to condense the volatilized solvent and toagglomerate the soapstock also while being stirred or agitated. Sincethe capacity of the pump is greater than the supply of the fluid systemto the economizer, the pump serves to draw a portion of the fluid systemfrom the cold coil 82. It will, therefore, be understood that the flowof fluid system to the economizer through the conduit 63 and the flowfrom the economizer through the conduit 100 are equal but that the flowthrough the pump 85, heater coil 90, hot coil 81, cooler coil 95, andcold coil 82 is at a substantially greater rate.

As described, the flow of the fluid system to the economizer and theflow from the economizer are continuous and equal. Also, theinputpressure and output pressure are preferably equal as are the inputtemperature and output temperature. With this in mind, it will beappreciated that as the system is heated in the coil and portions of thesolvent volatilized, there is a substantial volumetric increase whichresults in vigorous acceleration and agitation of the system in the coil90. Inversely,

- the cooling and condensing of the solvent in the coil results in acorresponding volumetric decrease also productive of agitation as thesystem is decelerated. 1nas-' much as the volumetric increase anddecrease are equal if the input and output temperatures and pressuresare equal, the system is readily balanced for operation.

In actual practice it is found that a three-phase system of thecharacter described can be reduced to a twophase system by a singlepassage through the heat exchanger described with the system requiringonly five or ten minutes in the heater 71 and a like period in thecooler 72. The recycling is advisable in commercial installations inorder absolutely to insure the elimination of all buoyant soapstock sothat as the system is discharged through the conduit 100 it consists ofthe miscella and soapstock which is heavier than the miscella andreadily removed therefrom by centrifugation. Not only does the practiceof the present invention enable the continuous, economical and effectiveremoval of the soapstock but it results in superior refined oil, theavoidance of solvent loss by entrapment in the soapstock, and theobtaining of a substantially solvent free soapstock as a byproduct ofthe operation;

Second form A second form of the present invention is shown in Fig. 3which makes provision for independent re-cy-cling through a heater and acooler. An economizer is shown at 169, a heater at 171 and a cooler at172. As before, the economizer has a first coil 180, a hot coil 181 anda cold coil 182. The first coil 180 is fed with the threephase systemfrom the conduit 63 in the manner previously described for the coil 80of theeconomizer 169. The heater 171 provides a coil 190 and the cooler172 pro vides a coil 195. The first coil 180 is connected to the coil195 which in turn is connected to the cold coil 182. The cold coil 182is connected to the coil 190 of the heater which in turn is connected tothe hot coil 181. The hot coil extends from'the economizer at 196 forconnection to a centrifuge, not shown, or other means forgravitationally separating the resultant two-phase system. As before,the economizer 169, heater 171, and cooler 172 may provide appropriateaveraging, heating and cooling means such as tanks 97, 98 and 99,respectively, in which the coils are contained. The tank 97 preferablycontains a heat transmitting fluid, the tank 98 is supplied with steamfor heating purposes and the tank 99 is chilled by water or suitablerefrigeration.

A pump 198 interconnects opposite ends of the coil 195 of the cooler172. Similarly, a pump 199 interconnect-s opposite ends of the coil 190in the heater 171. pumps are for the purpose of recycling the miscellathrough the cooler and through the heater. In the first form of theinvention, a pump, not shown, forces the miscella through thehomogenizer 60 and the heat exchanger at a rate of approximately twentygallons per minute in a commercial installation. The pump 85 has acapacity of approximately one hundred gallons per minute to achieve thedesired re-cycling through the exchanger. In this form of the inventioneach of the pumps 198 and 199 preferably have a capacity ofapproximately one hundred gallons per minute as the flow through theentire system is approximately twenty gallons per minute Thus, there isa vigorous re-cycling achieved in both the heater 171 and the cooler172.

Actually, because of vigorous agitation incident to volatilization inthe heater, the pump 199 is frequently not employed. However, there is afar greater tendency for soapstock to deposit in the cooler and the pump198 is preferably always utilized during operation of the second formthe invention now described.

Although the invention has been herein shown and described in what isconceived to be the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention, which is not to be limited to the details disclosed hereinbut is to'be accorded the full scope of the claims so as to embrace anyand all equivalent methods and processes.

Having described my invention, what I claim as ne and desire to secureby Letters Patent is:

l. A process for reducing a three-phase fluid system having agglomeratedsolid constituents in a liquid, some of which agglomerated solidconstituents are heavier than the liquid and others of which are lighterthan the liquid because of buoyant volatile material entrapped thereincomprising flowing the three-phase system through a closed conduit at apredetermined rate of flow, and successively heating and cooling thesystem in positions in spaced relation along the conduit whereby thesystem is agitated by successive acceleration and deceleration from saidpredetermined rate of flow caused by volumetric changes of the systemdue to the temperature changes concurrently respectively with heatingand expansion of the agglomerated solid constituents and entrappedbuoyant volatile material and cooling and contraction of said solidconstituents and buoyant material.

2. A process for reducing a three-phase fluid system havingagglomerations of solid constituents in a liquid, some of whichagglomerations are heavier than the liquid and others of which arelighter than the liquid because of volatile buoyant material entrappedtherein comprising flowing the three-phase system through a closedconduit, and successively heating and cooling the system in positions inspaced relation along the conduit, the heating being sufficient to raisethe temperature of the system including the entrapped material above thetemperature of the volatilization of said material and the cooling beingsufiicient to lower the temperature of the system below the condensationtemperature of said material.

3. A process for reducing a three-phase fluid system havingagglomerations of solid constituents in a liquid, some of whichagglomerations are heavier than the liquid and others of which arelighter than the liquid because of volatile buoyant material entrappedtherein comprising flowing the system through a closed conduit at apredetermined rate of flow while repeatedly and in rapid successionheating the system to a temperature sufficient to volatilize theentrapped material and cooling the system to a temperature sufficient tocondense said volatilized material whereby the system is agitated byacceleration from the predetermined flow rate concurrently withvolatilization of said material by volumetric changes of the system dueto the heating and whereby the system is agitated by deceleration tosaid predetermined flow rate caused by volumetric changes of the systemdue to cooling, which said agitation and successive volatilization andcondensation releases the buoyant material from the agglomerations.

4. A process for reducing a three-phase fluid system of a miscella ofoil and solvent containing agglomerated soapstock heavier than themiscella and agglomerated soapstock lighter than the miscella because ofsolvent entrapped therein to a two-phase system comprising successivelyheating the system to a temperature sufficient to soften the soapstockand to volatilize solvent contained therein and cooling the system to atemperature sufficient to condense the volatilized solvent and toagglomerate the soapstock, said heating and cooling being performed withthe system in continuous flow.

5. A process for reducing a three-phase fluid system of a miscella ofoil and solvent containing agglomerated soapstock which tends to settlein the miscella and agglomerated soapstock which tends to float in themiscella to a two-phase system preconditioned for gravitationalseparation comprising flowing the system through a closed conduit whilerepeatedly and in rapid succession heating the system to a temperaturesufficient to,

volatilize fractions of the solvent and cooling the system to atemperature sufficient to condense the volatilized. fractions of thesolvent.

6. A process for reducing a three-phase fluid system of a miscella ofoil and solventcontaining agglomerated soapstock heavier than themiscella and agglomerated soapstock lighter than the miscella because ofsolvent entrapped therein to a two-phase system preconditioned forgravitational separation comprising passing the fluid system through aclosed conduit having an intake end and an outlet end at a predeterminedrate of flow to and from the conduit, the fluid system having apredetermined temperature at the intake end, heating the fluid system ata position in spaced relation to the outlet end of the conduit, coolingthe fluid system at a position between the heating position and theoutlet end, said fluid system being heated above and cooled below thepredetermined intake temperature substantially equal amounts so that thetotal volume of the fluid system between the intake and outlet endsremains substantially constant, and recirculating the fluid system fromthe outlet end of the conduit to the intake end thereof at a flow rategreater than the predetermined flow rate to and from the conduit wherebythe recirculated portions of the fluid system are subjected to periodicheating and cooling actions.

7. A continuous process for reducing a three-phase fluid system of amiscella of oil and hexane containing agglomerations of soapstock, someof which agglomerations are heavier than the miscella and some of whichare lighter than the miscella because of hexane entrapped thereincomprising passing 'the system through a closed conduit having an intakeend and an outlet end at a predetermined rate of flow to and from theconduit, heating the fluid system at a position in spaced relation tothe outlet end of the conduit to a temperature above approximately 140F. but below approximately 158 F. to volatilize the hexane in theagglomerations and to soften the soapstock, and cooling the system at aposition between the heating position and the outlet end of the conduitto a temperature above approximately 80 F. and below approximately 115F. to condense the hexane and further to agglomerate and to harden thesoapstock.

8. A continuous process for reducing a three-phase fluid system of amiscella of oil and hexane containing agglomerations of soapstock, someof which agglomerations are heavier than the miscella" and some of whichare lighter than the miscella because of hexane entrapped thereincomprising passing the system through a closed conduit having an intakeend and an outlet end at a predetermined rate of flow to and from theconduit, heating the fluid system at a position in spaced relation tothe outlet end of the conduit to a temperature above approximately 140F. but below approximately 158 F. to volatilize the hexane in theagglomerations and to soften the soapstock, cooling the system at aposition between the heating position and-the outlet end of the conduitto a temperature above approximately F. and below approximately F. tocondense the hexane and further to agglomerate and to harden thesoapstock, and recirculating the fluid system from the outlet end of theconduit to the intake end thereof at a flow rate greater than thepredetermined flow rate to and from the conduit whereby the recirculatedportions of the fluid system are subjected to periodic heating andcooling actions.

9, A continuous process for preconditioning a fluid mixture of amiscella of oiland hexane containing agglomeration of soapstock, some ofwhich agglomerations are lighter than the miscella and some of which arelighter than the miscella because of hexane entrapped therein comprisingpassing the mixture through a closed conduit containing baflles whileheating the fluid to a temperature of from approximately F. toapproximately 158 F. whereby the mixture is agitated by the baffleswhile being heated and is further agitated by volatilization of thehexane, and immediately thereafter passing the previously heated andagitated fluid through a closed conduit containing baflies which iscontinuous with the preceding conduit while cooling the fluid to atemperature from approximately 80 F. to approximately 110 F. whereby thefluid is agitated during cooling, is further agitated by thecondensation of the hexane and a two-phase system is established.

References Cited in the file of this patent UNITED STATES PATENTS

1. A PROCESS FOR REDUCING A THREE-PHASE FLUID SYSTEM HAVING AGGLOMERATEDSOLID CONSTITUENTS IN A LIQUID, SOME OF WHICH AGGLOMERATED SOLIDCONSTITUENTS ARE HEAVIER THAN THE LIQUID AND OTHERS OF WHICH ARE LIGHTERTHAN THE LIQUID BECAUSE FLOWING BUOYANT VOLATILE MATERIAL ENTRAPPEDTHEREIN COMPRISING FLOWING THE THREE-PHASE SYSTEM THROUGH A CLOSEDCONDUIT AT A PREDETERMINED RATE OF FLOW, AND SUCCESSIVELY HEATING ANDCOOLING THE SYSTEM IN POSITIONS IN SPACED RELATION ALONG THE CONDUITWHEREBY THE SYSTEM IS AGITATED BY SUCESSIVE ACCELERATION ANDDECELERATION FROM SAID PREDETERMINED RATE OF FLOW CAUSED BY VOLUMERICCHANGES OF THE SYSTEM DUE TO THE TEMPERATURE CHANGES CONCURRENTLYRESPECTIVELY WITH HEATING AND EXPANSION OF THE AGGLOMERATED SOLIDCONSTITUENTS AND ENTRAPPED BUOYANT VOLATILE MATERIAL AND COOLING ANDCONTRACTION OF SAID SOLID CONSTITUENTS AND BUOYANT MATERIAL.